A-2 Appendix A: Hardware I/O Manual Document# 3PXCC4A3001
B&B Electronics Mfg Co – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics Ltd – Westlink Comm. Pk – Oranmore, Galway, Ireland – Ph +353 91-792444 – Fax +353 91-792445
Any eight-byte space not used by one of the devices listed in the
table and not used by any other equipment in your system may be
used for the serial port.
I/O Map of AT Class Machines
Hex Address Address Function in AT Class Machines
000-01F DMA controller #1 (8237A-5)
020-03F interrupt controller #1 (8259A)
040-05F timer (8254)
060-06F keyboard (8042)
070-07F NMI - non maskable interrupt & CMOS RAM
080-09F DMA page register (74LS612)
0A0-0BF interrupt controller #2 (8259A)
0C0-0DF DMA controller #2 (8237A)
0F0-0FF 80287 math c oprocessor
1F0-1F8 hard disk
200-20F game port joystick controller
258-25F Intel Above Board
278-27F parallel printer port 2
2E8-2EF COM4 serial port
2F8-2FF COM2 serial port
300-31F prototype card
378-37F parallel printer 1
380-38F SDLC or bisync com 2
3A0-3AF bisync com 1
3B0-3BF MDA - monochrome adapter
3BC-3BE parallel printer on monochrome adapter
3C0-3CF EGA - reserved
3D0-3D7 CGA - color graphics adapter
3E8-3EF COM 3 serial port
3F0-3F7 floppy diskette controller
3F8-3FF COM1 serial port